3 files changed, 54 insertions, 1 deletions

diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index 3ba7358ae5..dd9282a09e 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -524,6 +524,35 @@ static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
   llvm_unreachable("Invalid TLS model");
 }
 
+static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
+  switch (C.getSelectionKind()) {
+  case Comdat::Any:
+    return bitc::COMDAT_SELECTION_KIND_ANY;
+  case Comdat::ExactMatch:
+    return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
+  case Comdat::Largest:
+    return bitc::COMDAT_SELECTION_KIND_LARGEST;
+  case Comdat::NoDuplicates:
+    return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
+  case Comdat::SameSize:
+    return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
+  }
+  llvm_unreachable("Invalid selection kind");
+}
+
+static void writeComdats(const ValueEnumerator &VE, BitstreamWriter &Stream) {
+  SmallVector<uint8_t, 64> Vals;
+  for (const Comdat *C : VE.getComdats()) {
+    // COMDAT: [selection_kind, name]
+    Vals.push_back(getEncodedComdatSelectionKind(*C));
+    Vals.push_back(C->getName().size());
+    for (char Chr : C->getName())
+      Vals.push_back((unsigned char)Chr);
+    Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
+    Vals.clear();
+  }
+}
+
 // Emit top-level description of module, including target triple, inline asm,
 // descriptors for global variables, and function prototype info.
 static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
@@ -625,12 +654,14 @@ static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
     if (GV.isThreadLocal() ||
         GV.getVisibility() != GlobalValue::DefaultVisibility ||
         GV.hasUnnamedAddr() || GV.isExternallyInitialized() ||
-        GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass) {
+        GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
+        GV.hasComdat()) {
       Vals.push_back(getEncodedVisibility(GV));
       Vals.push_back(getEncodedThreadLocalMode(GV));
       Vals.push_back(GV.hasUnnamedAddr());
       Vals.push_back(GV.isExternallyInitialized());
       Vals.push_back(getEncodedDLLStorageClass(GV));
+      Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
     } else {
       AbbrevToUse = SimpleGVarAbbrev;
     }
@@ -656,6 +687,7 @@ static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
                                       : 0);
     Vals.push_back(getEncodedDLLStorageClass(F));
+    Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
 
     unsigned AbbrevToUse = 0;
     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
@@ -1915,6 +1947,8 @@ static void WriteModule(const Module *M, BitstreamWriter &Stream) {
   // Emit information describing all of the types in the module.
   WriteTypeTable(VE, Stream);
 
+  writeComdats(VE, Stream);
+
   // Emit top-level description of module, including target triple, inline asm,
   // descriptors for global variables, and function prototype info.
   WriteModuleInfo(M, VE, Stream);
diff --git a/lib/Bitcode/Writer/ValueEnumerator.cpp b/lib/Bitcode/Writer/ValueEnumerator.cpp
index befe15bb45..15f8034a36 100644
--- a/lib/Bitcode/Writer/ValueEnumerator.cpp
+++ b/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -117,6 +117,12 @@ unsigned ValueEnumerator::getInstructionID(const Instruction *Inst) const {
   return I->second;
 }
 
+unsigned ValueEnumerator::getComdatID(const Comdat *C) const {
+  unsigned ComdatID = Comdats.idFor(C);
+  assert(ComdatID && "Comdat not found!");
+  return ComdatID;
+}
+
 void ValueEnumerator::setInstructionID(const Instruction *I) {
   InstructionMap[I] = InstructionCount++;
 }
@@ -307,6 +313,10 @@ void ValueEnumerator::EnumerateValue(const Value *V) {
     return;
   }
 
+  if (auto *GO = dyn_cast<GlobalObject>(V))
+    if (const Comdat *C = GO->getComdat())
+      Comdats.insert(C);
+
   // Enumerate the type of this value.
   EnumerateType(V->getType());
 
diff --git a/lib/Bitcode/Writer/ValueEnumerator.h b/lib/Bitcode/Writer/ValueEnumerator.h
index d1ca15f45d..1c9f38e07b 100644
--- a/lib/Bitcode/Writer/ValueEnumerator.h
+++ b/lib/Bitcode/Writer/ValueEnumerator.h
@@ -16,6 +16,7 @@
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/UniqueVector.h"
 #include "llvm/IR/Attributes.h"
 #include <vector>
 
@@ -25,6 +26,7 @@ class Type;
 class Value;
 class Instruction;
 class BasicBlock;
+class Comdat;
 class Function;
 class Module;
 class MDNode;
@@ -48,6 +50,10 @@ private:
   typedef DenseMap<const Value*, unsigned> ValueMapType;
   ValueMapType ValueMap;
   ValueList Values;
+
+  typedef UniqueVector<const Comdat *> ComdatSetType;
+  ComdatSetType Comdats;
+
   ValueList MDValues;
   SmallVector<const MDNode *, 8> FunctionLocalMDs;
   ValueMapType MDValueMap;
@@ -139,6 +145,9 @@ public:
     return AttributeGroups;
   }
 
+  const ComdatSetType &getComdats() const { return Comdats; }
+  unsigned getComdatID(const Comdat *C) const;
+
   /// getGlobalBasicBlockID - This returns the function-specific ID for the
   /// specified basic block.  This is relatively expensive information, so it
   /// should only be used by rare constructs such as address-of-label.